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Vacuum, Brake Booster, LS6 Intake Mod - HELP

This is a discussion on Vacuum, Brake Booster, LS6 Intake Mod - HELP within the General Help forums, part of the LSx Technical Help Section category; Greetings folks. It's been a LONG time since I have revisited the site. My build has pretty much been a ...

  1. #1
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    Dark Silver
    '73 240Z w/ LS1 & T56

    Vacuum, Brake Booster, LS6 Intake Mod - HELP

    Greetings folks. It's been a LONG time since I have revisited the site. My build has pretty much been a nightmare from the get go. I have plugged along. Gotten past some REALLY Bad Advice on things, etc. I have Re-Read posts regarding the LS1-LS6 Intake Swap. I have the How-To. But, I seem to be missing something that I have yet to pinpoint in my Searches.

    I did the Intake Swap, following all directions. I had a shop "Tune" my Holley EFi [another Nightmare ... runs BADLY]. They suggested a Catch Can in my PCV system. No problem ... Added. Car runs like SHITE with Drivers PCV plugged and Passenger [rear] PCV capped. It also runs like crap if I put an actual PCV Valve in drivers rear, and connect to passenger's rear valve cover.

    But my REAL problem is where brakes are concerned. I have replaced ALL of my brake components, in fact replaced NEW with NEW. Bled, bled, and bled some more. Pedal is FIRM. Alignment shop says Booster must be bad. Replaced that. No go.

    Here is where the Tie-In is ... the barbed tube on the Back of the LS6 Intake [OPSU ?] has Strong SUCTION .... whether I hook PCV up, or plug/cap per the How To. If I put my thumb over it, engine stalls. THAT Barb is what is supposed to be [Pushing] air into my Brake Booster ... ISN'T IT ?

    I genuinely apologize of this is an excruciatingly STUPID Question; but, have some empathy. I have struggled for YEARS to get my build done. Been victimized more times that I have dollars. And, I just want to DRIVE my car [Safely].

    PLEASE HELP

  2. #2
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    It is a "vacuum" assisted booster - meaning there should be suction, not pressure. The barb is correct.

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    Quote Originally Posted by pajeff02 View Post
    It is a "vacuum" assisted booster - meaning there should be suction, not pressure. The barb is correct.

    OK ... Thanks. So, I'm guessing that the Check Valve is in the wrong direction. I can Blow into hose TOWARD Brake Booster from Intake, and air passes. I CANNOT blow From Booster to Intake. That is installed INCORRECTLY ??

    Anything else seem [Wrong] from my description ?

    Thanks for reading ....

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    Sounds like you need to switch it around.

    The stock PCV system runs from the back of the driver side rocker cover, to a "Y" fitting that goes to the passenger side rocker cover and then to the PCV valve which is mounted in the hose that runs to the side of the intake. Simply connecting the two sides together does nothing, it needs a vacuum source and i do recommend running a PCV setup, with a catch can like your tuner recommended. Is it idling high, stalling or what?

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    Thanks ...
    If I plug barb at back of intake, it stalls. Bear in mind, I am running the LS6 Intake Swap, which has an entirely different PCV. I am already running much more tubing than those who jut do the Swap from the HowTo

    Thank you

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    Our car also has the LS6 intake on it and I have replaced the entire PCV system and installed a catch can. If plugging the barb stalls the car, you do not have enough air flow at idle. Has the IAC been calibrated?

    (I assume you have a cable actuated throttle body with an integral Idle Air Control (IAC) valve. I assume you are running a stock style GM PCM and that your engine is equipped with a MAP sensor at the back of the intake? Do you have a MAF, or is it running a speed density tune? If any of my assumptions are incorrect, let me know.)

    Do you have access to a scanner that will read live data?

    I am shutting down for the evening here and we can pick this up again over the weekend.

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    Thank you Jeff !

    I have cable TB. It is running of [Poorly Tuned] Holley EFI system. Shop told me that they replaced IAC

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    Since you're indulging my ignorance, I wanted to give as thorough a 'picture' as possible.
    Engine '99 TransAm LS1
    Intake LS6 [w/ valley cover, 'vent' tubes ?, etc.]
    TB OE Cable Actuated
    Eng Mgmt Holley EFI [tuned by a shop who didn't know what they are doing]
    Cam Mild Lunati
    Heads MILD rework after repair
    No AC / PS
    Smog Exempt
    Have Fact Svc Manuals to try and "learn"
    Oil Catch can connected to barb from Valley Cover UNDER TB, and to Intake [+Check Valve on this line]
    Front of Pass. Valve cover connected to TB
    Rear Drivers Valve Cover has PCV, then to Rear Passengers. The HowTo tells readers to Cap/Plug

    The car has run Very, VERY Rich since ... "Tuning". But it ran ..... now it doesn't. I have been trying to resolve numerous [other] issues [whole car electrical, brakes, exhaust ...] before paying yet another shop to 'tune' it. I do NOT know how to do ANY Eng Mgmt Computer work ... [I'm 50, and BARELY capable of using my Mac]

    I don't think I have enough posts, or I simply do not know how to post pics; but, I can email any detailed pics of interest ...

    THANKS

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    Do you have an OBDII port wired into your car? I am not familiar with the Holley EFI system. Fueling is a function of taking the data from multiple engine sensor outputs and using this data to determine just how long to open the injectors to squirt the proper amount of fuel into the combustion chambers. Things that really mess this process up are vacuum leaks, exhaust leaks between the heads and the upstream O2 sensors, and mismatched or defective parts. Once the engine warms up and switches from open to closed loop fueling, the computer should be looking at the O2 sensor data to adjust fueling on the fly.

    In setting up the Holley system, I assume that certain information had to be input into the ECM and if this information was incorrect the system will not be able to function properly. A scanner would help you track down any bad sensor outputs if you have an OBDII port. Any idea if the shop correctly determined your fuel injector parameters? Although a 26 lb. injector is a 26 lb. injector, they all have unique characteristics that have to be accounted for in the tuning from one brand to another. Just a few thoughts...

    Pics would be nice and you can click on my site name to email me if you cannot post them in the thread. Posting pics requires opening a free account at a site like Photobucket or Image Shack, uploading the pics from your computer to the photo hosting site, and then copying and pasting the [IMG] code into your post on here.

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    Dark Silver
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    No OBD port w/ Holley.
    I'm getting [more] confused ... so, should I REVERSE the Check Valve between the back of the Intake and the Brake Booster ? What is accomplished w/ the Y that you spoke of ? Where does [third] leg of Y connect if two go to rear part of each Valve Cover ?

    THANKS !!

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    Take the valve and blow through it. The end you can blow through should face the booster.

    This should explain it:


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    Pretty tragic ... TWO different automotive 'professionals', telling me to replace this, that must be bad .....
    And all it was is merely a $1.50 Check Valve inverted in line !!

    THAT'S why I am Balding ....

    THANKS

    Still unsure about the rest of it [your connections Post-LS6 Swap]

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    Wish you weren't on the other side of the country - I love brain teasers like this!

    How is the Holley ECU adjusted - does it have a handheld controller, or does it plug into a laptop?

  14. #14
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    USB and/or Handheld. I have USB cord only

    Thanks

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    Let's see some pics of this project - underhood shots, the ECU, the connectors at the ECU and around the engine, please.

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